High Post-Treatment Leptin Concentration as a Prognostic Biomarker of the High Risk of Luminal Breast Cancer Relapse: A Six-Year Comprehensive Study

(1) Background: Nowadays, obesity is well-recognised as a significant risk factor for many chronic diseases, for example, hypertension, diabetes, atherosclerosis and cancer. This study is designed to investigate the prognostic value of the pre- and post-treatment serum levels of adiponectin and leptin in luminal A and B invasive breast cancer (IBrC) patients based on six-years follow-up. (2) Methods: Among 70 patients who underwent breast surgery, 35 were Stage I and 35 were Stage II. The concentrations of pre- and post-treatment adiponectin and leptin were evaluated with a specific ELISA kit. The median follow-up was 68.5 months (inter-quartile range (IQR) = 59–72 months) with a recurrence rate of 15.71%. (3) Results: Generally, concentrations of leptin and adiponectin increased after adjuvant therapy. Follow-up showed a significantly higher incidence of disease relapse in IBrC patients with a high post-treatment concentration of leptin (25.71% vs. 5.71% of cases with a low post-treatment concentration of leptin). A post-treatment leptin concentration of 26.88 ng/mL with a specificity of 64.9% and a sensitivity of 88.9% was determined as the best cut-off value to distinguish patients with disease recurrence from those without disease relapse. (4) Conclusions: Our results demonstrated that only the post-treatment serum leptin concentration may be of value as a prognostic indicator and could contribute to predicting a future outcome for patients with early-stage IBrC.